Treatment of inhibitors



Patented July. 12, 1938] UNITED versal Oil Products Company, Chicago, Ili.,

a corporation of Delaware No Drawing. Application November 17, 1934,

. Serial No. 753,510

9 Claims. (01.23-239) This invention relates to thetreatment of inhibitors and refers more particularly to the treatment of a certain class of inhibitors which which represent a class ofsemi-refined inhibit 10 ing materials which are cheap and easily procurable. and which have equal or better inhibiting value than the majority of individual chemical compounds used for inhibiting purposes. The present invention is particularly directed to the purification and improvement of tars and fractionsrthereof produced from the distillation ofvarious types of wood, although it is also applicable to the treatment of other heavy tars such as those produced from coal, lignite, etc.

The value of wood tar fractions as inhibitors of gum' formation, color depreciation and loss in antiknock value is affected by a number of factors such as, for example, the readiness with which, the gasolineto be inhibited oxidizes and 25 p lymerizes under average storage conditions and on the side of the wood tar itself by the source, type and age of the wood distilled and the conditionsof distillation'such as, for exam-- primary distillation of various woods are all as serviceable to some extent as inhibitors in un stable gasolines, experience has shown that it is preferable touse selected intermediate cuts for several reasons. In the first place, the lower tboiling fractions, say those boiling below 425- 40 464 :-F'., have-generally a considerably lower in- -.hibiting potency than those boiling within the range of 464-572 F., and particularly those boiling between 464-536 .F., the-last fraction named being particularly efficient in practically all 45-}cases. The. lower boiling fractions are at the present time practically never utilized as inhibitors on account of the excessive quantities rejduiired to effect stabilization and the fractions boiling-above 572. F. contain such. quantities of so heavy' pitches that their use is precluded on account 'of the. eilfect 'which the requisite quantities 1 have on the color, color stability and'transluce'ncy of 'the gasoline. During storage of wood tarsor'their fractions theirisfrequently a de- 55 velopment of relatively high boiling pitchy materials which lower the value of the woodtar out when used in gasoline.

In one specific embodiment the present invention comprises the treatment of wood tars or fractions thereof intended for use as inhibitors in gasoline by polymerizing agents comprising heavy metal salts, treatments being conducted in either liquid or vapor phase.

The preferred'treatlng materials according to the process of .the present invention comprise such compounds as the halides, and particularly the chlorides of such metals as aluminum, zinc, tin, iron, etc., which have known value as reagents for effecting polymerization or condensation reactions. The sulphates of these metals and other inorganic salts may sometimes be used in lieu of the preferred halides. While the alternative use of different salts of this character is comprised within the scope of the invention, it is not to be. assumed that they will be equivalents in their action upon different wood tar fractions under conditions of treatment which may be varied 'to produce the desired refining tions by the use of the preferred treating materials are in 'general those of polymerization and/or condensation among the molecules of the constituent compounds. It is observable that there is a general elevation of the boiling point curve, and it has been found that the percentage yield of the intermediate fractions most service- .able as inhibiting material is practically always liquid phase the viscosity of heavy cuts may be reduced by the use of solvents to produce a fluid which is morereadily contacted with the polymerizing agents and from which the polymerized materials are more readily separable either by settling or filtering. This dilution or cutting back of the tar while not a special feature of the invention is generally preferable in liquid phase treatments. In such cases after the treatment is eifected the subsequent distillation removes the solvent as. a primary light cut and the desired treated wood tar fraction as an intermediate or heart out and leaves the heavy a'sphaltic .polymers as a residue covered fractions.

The polymerizing salts may be used either as solids or in solution. Such salts as aluminum chloride are best used in anhydrous condition.

and in liquid phase treatments the pulverized salt may be mechanically agitated with a cutback wood tar fraction. in small quantities. Ferric chloride may be used in a similar manner or in solution, while the chlorides of zinc -and tin may be employed in solutions of controlled concentration usually approaching saturation. The

amounts of these reagents necessaryfor effective treatments .will vary with their inherent polymerizing power and the degree of treatment most desirable on the particular fractions of wood tar undergoing treatment, though the'ainounts are usually small and the process is thus economical.

As a rule the amount of reagent employed, calculated on the basis of the anhydrous salt, seldom exceeds 5 per cent by weight of the wood tar fraction treated. From this figu e the amounts used may range down tovas low as 0.5 per cent, as

pitches and other reaction products ofa com-.

plicated character, including metallo-organic ad'- dition complexes, and it may be conducted under.

varying pressures at different stages, that is in re moving any light solvent'which may. have been employed, atmospheric pressure may be satisfactory while reduced'pressures corresponding to a high degree of vacuum may produce the best results in the recovery of the treated tar fraction as a heart cut.

As an alternative mode of treatment the vapors of a wood tar or fraction thereof may be treated when under a considerable vacuum corresponding generally to less than 10 mm. of mercury so that the vapor temperature is kept low. As a general rule unless this point is observed the reactions of polymerization take place to too great an extent, causing undue loss of material and sometimes lossv of inhibiting value In conducting vapor phase treatments the tar fractions to be treated are distilled either from batch or continuous stills and contacted with polymerizing salts in treaters which may either contain composite contact masses comprising relativelyinertmaterialscontainingregulatedamounts of polymerizing salts or which may function as fractionators, in which case solutions of salts, such as for example zinc chloride, may be passed counterflowto the vapors. In the latter case the tower may contain filling material such as regularly spaced pans or trays of some character or may be filled with silica fragments, Raschig rings or some other form of filler adapted to break up the streams of solution and cause closer contact with the vapors. The concentration of the solutions employed to effect the vapor phase treatment will approach saturation and may be maintained by the presence of steam in the vapors to prevent undue concentration of the solution .and

consequent separation of the solute.

As an alternative mode of vapor phase treatin re" ment such salts as, aluminum chloride may be introduced intothe vapors in vapor form and substantially anhydrouscondition or concentrated solutions of other salts not subject to extensive hydrolysis may be injected or atomized into the vapor stream, The separation of polymers and sludge products needs no special description as this may be accomplished by any common means.

The treated vapors may be fractionated. de-

sures although as a vrule the easiest mode'of operation is toinaintain vacuum through. the

fractionator and in the receiver for finished product by withdrawing flxedgases from the re- Example 1 In this instance a hardwood tar having. 55.3 per cent by volume boiling within the range of 356-435 F. and 31.7- per cent by volume boiling between 425-572 F., was taken fortreatment. The inhibiting value of the light and intermediate fractions was taken as proportional to the increase in induction period in the currently used oxygen bomb test produced by the addition of 0.05 per cent of the fraction to a paramnic cracked gasoline. In the case of the lower boiling fraction the increase in the time .to 'measurableoxygen absorption was 300 minutes, while that produced by the heavier fraction mentioned was 970 minutes. a

p The whole wood tar containing the fractions mentioned was treated with 5 per cent by weight of thepowdered zinc chloride at a temperature of about 250 F. and atmospheric pressure. The

products ofthis reaction were subjected to a vacuum distillation and it was .then found that the percentage of material boiling below 425 1''.

.had been reduced to 30 per cent of the whole ta'r,

while the fraction boiling between 425-572'1".

- had been increased to 48 per cent on the same basis. The inhibiting values measured by the induction periods were 440 and 1300 minutes, respectively. The remaining portions of the tar were;1 left in the distillation retort as a heavy pitc Both fractions were found to have a'much lighter color than the corresponding boiling range cuts from the original tar and improved color stability.

- Example 2 In this case a low boiling'fraction constituting 45 per cent of another wood tar and boilingbelow 425 F. was treated with about 3 per cent by weight of anhydrous aluminum chloride at the same temperature as in Example 1 The low boiling-fraction before treatment increased the -induction period of the paramnic cracked gasoline by about 300 minutes when used in an amount or 0.02 per cent by weight of the gasoline. As a result of the treatment and-the suixequent distillation, the boiling range of the'iraction was increased so that 60 per cent boiled within'the range of 425-572 F., and the induction period increase produced by 0.02 per cent by weight of Again both color and color stability were improved.

. sired either under vacuum or under normal pres- Example 3 When adding a fresh tar fraction boiling between 425-536 F. to a gasoline of 30 color on the Saybolt scale in amounts of 0.05 per cent the color was affected but little so that the drop was only to 29 on the Saybolt scale. However, after storage of the tar for a period of several months the eflect of the addition of the required amount nal valuable properties of the wood tar had been entirely, restored with only minor losses in volume, less than 5 per cent. It was also found that the color stability of the gasoline was better after the addition of the required amount of treated wood tar. The general results of the treatment may be summarized in the following table showing the results with cracked gasolines from different charging stocks.

Color and color stability of uninhibited and inhibited gasoline No in- Fresh inhibhibitor itor Treated in- Aged inhibiitor hibitor Inhibitor, per cent Pennsylvania gasoline Oaliiorma gasoline Mid-Continent gasoline standardized are light test which is roughly equivalent to two hours exposure to full June sunlight. An analysis of the data shows that both the color and color stability of the-three gasolines was worse when using the aged tar fraction than when using the fresh tar fraction and that the fraction restored by treatment according to the present process was somewhat better'than the original fresh tar fraction, thus indicating'definitely the value of the invention from a commercial standpoint. I

Substantially the same results are obtainable'when treating the above mentioned fraction in vapor phase if the zinc chloride solution is atomized into the vapors as they enter a settling chamber.

The nature of the invention is sufficiently described in the specification and the results obtainable by its use are exemplified by the numerical data used but the invention is broad in scope and is not to be unduly limited by the descriptive material and eiramples.

I claim as my invention:

i. A process for the treatment of wood tar to improve its inhibiting properties in respect to preventing deterioration of motor fuels which comprises, subjecting the said wood tar to a polymerizing treatment in the presence of a polymerizing salt of a metal.

2. A process for the treatment of wood tar to improve its inhibiting properties in respect to preventing deterioration of motor fuels which comprises, subjecting the said wood tar to a polymerizing treatment in the presence of a polymerizing metallic halide. I

3. A process for the treatment of a tar derived from hardwood to improve its inhibitingproperties in respect to preventing deterioration of motor fuels which comprises, subjecting the said tar to a polymerizing treatment in the presence of a polymerizing metallic halide.

4. A process for the treatment of a fraction derived from wood tar to improve its qualities as an inhibitor in preventing the deterioration of cracked gasoline in respect to the formation of gum which comprises, subjecting the said fraction derived from wood tar to a polymerizing treatment in the presence of a polymerizing chloride of a metal.

5. A process for the treatment of a fraction derived from hardwood tar to improve its quaiities as an inhibitor in preventing the deterioration of cracked gasoline in respect to the formation of gum which comprises, subjecting the said fraction derived from hardwood tar to a polymerizing treatmentin the presence of a polymerizing chloride of a metal.

6. A process for the treatment of a distillate derived from wood tar to improve its qualities as an inhibitor in preventing the deterioration of cracked gasoline in respect to the formation of gum which comprises, subjecting the said distillate derived from wood tar to a polymerizing treatment in the presence of a polymerizing chloride of a metal.

7. A process for the treatment of a distillate derived from wood tar boiling substantially below 425 F. to improve its qualities as an inhibitor in preventing the deterioration of cracked gasoline in respect to the formation of gum which comprises, subjecting the said distillate derived from wood tar boiling substantially below 425 F. to a polymerizing treatment in the presence of a polymerizing chloride of a metal.

8. A process for the treatment of a fraction an inhibitor in preventing the deterioration of cracked gasoline in respect to the formation of gum which comprises, subjecting the said fraction derived from wood tar to a polymerizing treatment in the presence of zinc chloride.

9. A process for the treatment of a distillate derived from wood tar boiling substantially below 425 F. to improve its qualities as an inhibitor in preventing the deterioration of cracked gasoline in respect to the formation of gum which derived from wood tar to improve its qualities as v 

